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An aircraft's Aircraft Communications Addressing and Reporting System uses line of sight HF via ground stations or satellites to communicate with its base station.

This system allows for three types of messages to be sent:

  • Air Traffic Control
  • Aeronautical Operational Control
  • Airline Administrative Control

Aeronautical operational control and airline administrative control messages are used to communicate between the aircraft and its base. Various types of messages are possible, for example, relating to fuel consumption, engine performance data, aircraft position, in addition to free text.

So, questions:

  • Can ACARS be turned off? Would this generate a warning at the base station?
  • Can ACARS send postion, altitude and heading information automatically?
  • Can ACARS be repeatedly pinged to track an aircraft's position and heading? Would this require any intervention by the pilots? (posted separately)
  • Is this system standard on commercial airliners?
  • What data do Airlines collect from the ACARS, if any at all?
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anything on a plane can be turned off –  ratchet freak Mar 14 at 15:12
    
ACARS can also use VHF for comms (not just HF). –  casey Mar 14 at 20:01

3 Answers 3

  • Can ACARS be turned off? Would this generate a warning at the base station?

Yes, ACARS can be turned off. See another answer of mine for more details. Typically other systems use ACARS to send reports on a regular basis to update position and track other information, plus on an "as-needed" basis for abnormal things. It would be up to the individual airline to look for these reports and to generate a warning if one didn't check in at the expected time, but I don't believe that they do this. There is a lot of variation in the communication systems and they aren't 100% reliable so a lot of false alarms would be triggered.

  • Can ACARS send postion, altitude and heading information automatically?

ACARS itself can not, but other systems like the Flight Management Systems (FMS) or ADS-C on board the aircraft can use ACARS to send reports like this automatically, and in some cases they do.

  • Can ACARS be pinged to track an aircraft's position and heading? Would this require any intervention by the pilots?

Again, ACARS is simply a communication system. A message can be sent via ACARS which will forward to the appropriate system requesting this information and have it respond.

  • Is this system standard on commercial airliners?

I believe that most airliners that travel over international waters have ACARS, but I'm not sure if it's a requirement or not.

  • What data do Airlines collect from the ACARS, if any at all?

This varies from airline to airline, but messages at the beginning and end of the flight (used to track flight time, etc.) and periodically during the flight are typical. Usually periodic position updates and abnormal system indications are included as well.

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  • Can ACARS be turned off? Would this generate a warning at the base station?

Everything can be turned off, especially in an aircraft. It will probably not generate a warning at the base station immediately, because long distance data comms are not always reliable. It would cause too many false warnings.

  • Can ACARS send position, altitude and heading information automatically?

Yes, ADS-C (Automatic Dependent Surveillance - Contract) provides such functionality over ACARS for ATC purposes. ATC have to establish the link first to get the reports automatically.

  • Can ACARS be pinged to track an aircraft's position and heading? Would this require any intervention by the pilots?

Using ADS-C position can be extracted by ATC, and the airline can do the same. Intervention by the pilots is not needed

  • Was this system installed and functional on MAS370?

Installed yes, functional I don't know.

  • What data does Malaysian Airlines collect from the ACARS, if any at all?

I have no idea.

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ACARS does not include coordinates. It does include airspeed and altitude, as these are of interest for engine health. ACARS was functional on the Malaysian air flight, it was stated that before it went of radar, several messages were received.

A good starting point on ACARS can be found on SKYbrary.

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ACARS can include coordinates. Simply said, ACARS are the SMS text messages of aviation. You can transmit position over ACARS just as you can do it over SMS text. –  DeltaLima Mar 14 at 16:13

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